The present invention relates generally to an illumination device. More particularly, the present invention relates to an illumination device for producing a concentrated directional light beam for use in verifying a center plane of boring, for example, in an underground mine passageway.
During underground mining, it is important to maintain the direction of boring of the mine passageway along a predetermined horizontal path. By maintaining the predetermined path, the mine passageway is more advantageously arranged within the coal or other ore to be mined. In the past, a deviation of several feet per 100 feet of boring is not uncommon. Such a deviation, if permitted to continue, is unacceptable.
One known method of verifying the vertical center plane of the boring includes requiring an engineer/surveyor to arrange appropriate surveying instruments within the bored passageway at periodic intervals to verify the center plane of the passageway. This procedure requires costly time consuming measures to reset the instruments and requires the additional expense of paying the engineer/surveyor's time. Accordingly, such a procedure is neither expeditious nor economical.
Accordingly, it is an object of the present invention to provide a simple and effective method of verifying the center plane of a boring in a mine passageway.
A further object of the present invention is to provide an apparatus which permits the periodic verification of the center plane without requiring the services of an engineer/surveyor.
Still further, it is an object of the present invention to provide a relatively simple illumination device for producing a directional light beam which may be used for verifying the center plane of an underground mine passageway. The illumination device according to the present invention can preferably be left within the passageway to be used for a periodic verification of the center plane without interfering with the mining operations therein.
It is another aspect of the present invention to provide a novel illumination device for producing a directional light beam which may be conveniently secured to a support and used for illuminating a predetermined small area spaced from the support.
These and many other objects are achieved by an illumination device for producing a concentrated directional light beam according to the present invention. The illumination device includes an elongated first portion having a longitudinal axis. A fastening arrangement is provided for securing the first portion to a support structure. A second portion rotatably received by the first portion contains a light source for producing the directional light beam. The light beam is adapted to be directed away from the longitudinal axis of the first portion. An arrangement is provided for retaining the second portion in a predetermined angular position with respect to the longitudinal axis of the first portion.
According to a preferred embodiment, the second portion is telescopically received within the first portion. Upon extension of the second portion, a hinge arrangement is exposed which arrangement permits movement of the light beam produced by the light source from a direction substantially colinear with the longitudinal axis of the first portion to a direction substantially perpendicular to the longitudinal axis. Still further, the second portion may be selectively retained in the position substantially perpendicular to the longitudinal axis of the first portion.
Still further in the preferred embodiment, the fastening arrangement includes an expandable chuck carried by the first portion of the illumination device. The second portion is adapted to interconnect with an actuator for the expandable chuck in a first, closed position of the second portion relative to the first portion. By this arrangement, rotation of the second portion in the first position is operable to expand the chuck and secure the chuck within an opening provided in the support structure. Still further, a switch for energizing the light source is arranged to close when the second portion of the illumination device is moved away from the first position of the second portion. The illumination device also preferably includes a vernier scale secured to the first portion and adapted to indicate the angular position of the second portion relative to the longitudinal axis of the first portion.
In accordance with a method of verifying the center plane of boring an underground mine passageway according to the present invention, a first portion of an illumination device is secured against rotation relative to a wall of a mine passageway. The second portion is rotated generally about a vertical axis until the second portion is secured in a predetermined angular position indicative of the desired center plane. In this way, the light beam is directed against an end wall of the underground mine for indicating the center plane of boring. The location of the light beam upon the end wall is preferably marked such that the boring equipment may be moved into place and aligned with the marking.
According to the preferred method of arranging the second portion at the predetermined angular position, the second portion which is telescopically received within the first portion is extended after securing the first portion relative to the wall. The second portion is subsequently pivoted about an axis perpendicular to the vertical axis before rotating the second portion about the vertical axis.